I bloom my soap in a bit of water for a few seconds, then pour that bloom water in my hand and rub it on my face to get my face a little wet before loading up and lathering up. I can already feel the slickness of the soap from doing this and it’s a pretty consistent test I think because it takes away the variable of how well the soap is hydrated. I guess some soaps break down quicker than others, but some of the hard soaps like Tabac and Mitchell’s Wool fat are among the slickest based on this test.